Data Sets for EPILOG Data Stores (EDS) keep getting marked as 'unavailable invalid'.
There is nothing wrong with the EPILOG EDS, but they keep getting flagged as 'invalid'.
Diagnosing the problem
Using a non-IBM product, such as StopX37, to monitor space related issues, you may find that product creates a secondary extent for the EDS, even when it is not requested. We do not recommend using extents for EPILOG EDS.
Resolving the problem
Define EPILOG EDS without any extents. In this case after turning off StopX37 to the EPILOG EDS files, EPILOG switching of EDS works as designed.